The first information about such devices relates to the end of the 1980's . Some works, describing the application of X-ray lenses in lithography devices, one can find in: “Book of Abstracts. 3rd All-Union Conference on Relativistic Particles Radiation in Crystals. May 25-30, 1988”. (Nalchik, 1988) [1]. If a divergent radiation source is used these devices comprise a lens, transforming the radiation to a quasi-parallel one directed through the mask on the resist, applied on the substrate. The lens comprises a set of channels for directing radiation curved along a barrel-shaped generatrix. An effect of multiple total external reflections from the walls of the channels is used when a radiation is transmitted. As a whole, a lens for a divergent radiation changing to a quasi-parallel one is half barrel-shaped and it is called a half lens as distinguished from a full lens, which focuses a divergent X-rays and is barrel-shaped.
More detailed information about the X-ray lithography devices including all elements of such devices mentioned above are described in the review “Multiple Reflection From Surface X-ray Optics,” (M. A. Kumakhov and F. F. Komarov. PHYSICS REPORTS. A review Section of Physics Letters, volume 191, number 5, August 1990. North-Holland) [2], p. 345-348).
Non-uniform radiation intensity decreasing toward a periphery of the output face of a lens, falling on a mask, is a disadvantage of the described prior art devices. It becomes necessary to use filters in order to absorb “extra” radiation in the central section of the emergent beam of the lens. This solution was mentioned in source [1], however a structure of the device, comprising a filter, as a whole is described in U.S. Pat. No. 5,175,755 [3] (published Dec. 29, 1992). Locating the absorbing filter after the half lens, before or after the mask, is described in this patent.
The second mentioned variant of placing an absorbing filter is obviously poor, as according to this variant a radiation of extra intensity exposures on the central part of the mask, being an expensive precise unit, will result in destruction of the mask Further, the influence of actual out-of-parallelism of emergent radiation of a half lens appears in this variant to a greater extent. This radiation divergence determines the increased spreading of shadowgraph after the mask the greater the distance after the mask. Placing the filter after the mask inevitably increases this distance.
The first variant i.e., placing a filter between a half lens and a mask, is more desirable. However according to this variant as well a radiation, which extra intensity should be attenuated, passes through another expensive unit of the device, an X-ray half lens, what results in its aging.
The influence of the aforesaid factors leads to refusal of usage of absorbing filters, in particular if it is necessary “to smooth” great difference between a radiation intensity in the central and peripheral parts of the cross-section of the emergent beam, when a radiation intensity, being transported along the central channels of the lens, exceeds a lot a radiation intensity after the filter. This, in its turn, requires the use of rather “thin” lenses for making the difference small. Such lenses have a small capture angle of radiation, emerging from the source.
Also, fostering the usage of “thin” lenses with a rather small capture angle in X-ray lithography, is a sharp drop of transmission coefficient of a lens at a radiation rotation angle (when a half lens is used it is equal to a half of a capture angle) exceeding some limit value. So, according to calculations (see the results in source [2], p. 318), this value is equal to 0.3-0.40 radian. As this effect is well known, it is considered that further increasing of a capture angle will not increase an integral intensity of an emergent beam. The necessity to suppress a radiation intensity in the center of the beam “to equalize” it with a low peripheral level of intensity seems to be a very strong factor, making no point in using a small capture angle in lithography. So, for instance, in the work: M. A Kumakhov. “State and Perspectives of Capillary Roentgen Optics,” Proceedings of SPIE—The International Society for Optical Engineering. Volume 2011, 14-16 Jul. 1993, San Diego, Calif. [4] real lithography devices with a capture angle of a half lens from 0.15 up to 0.3 radian are described. Such half lenses capture not more than 1-2% of an isotope source radiation.
Another result of using “thin” half lenses is a small cross-section of the emergent beam, what makes possible to irradiate only a small part of the substrate area with a resist, applied on it. To process the whole area it is necessary to use stepwise irradiation. In spite of using special high-precise devices for this purpose, it is impossible to avoid errors, caused by errors in conjugation of neighboring zones under exposure.
Thus, the present invention is aimed at obtaining a technical result, implying that the usage of a source radiation increases simultaneously with enlarging of the area of a plate under exposure and increasing a lens longevity. This technical result can be obtained owing to the combination of two expedients: (1) an absorbing filter is placed between a source and a half lens and (2) a half lens with larger capture angle is used. For the latter an existence of an optimum value, considerably exceeding the aforesaid limit values and depending on an energy of the used radiation and material properties of reflecting surfaces of the channels of a half lens (i.e. a material, the channels are made of if they are not applied, or a material applied if exists), has revealed. In the energy range of a radiation being used from 0.6 keV up to 6 keV an optimum value of a capture angle depends only on a radiation energy. A material, a reflecting surface of the channels is made of, can be any one, feasible from the technological point of view for producing the channels of an X-ray lens or for their inner surface applying on condition that it contains only light elements, i.e., the atomic number should be not more than 22.
Further, U.S. Pat. No. 5,175,755 described a source of a soft X-rays, a half lens for a divergent radiation of this source transforming to a quasi-parallel one, the lens includes a set of channels for transmitting radiation with a total external reflection, and the channels are oriented along a generatrix of barrel-shaped surfaces, the means for placing a mask and a substrate with a resist applied on it being located on the side of an output face of a half lens, and an absorbing filter for smoothing a nonuniformity of a beam intensity of an emergent radiation of a half lens, so that the intensity decreases from the center to the beam periphery.
Contrary to the suggested device, an absorbing filter is placed between a radiation source and an input face of a half lens, and the relationship of the half lens cross sizes and a focal distance from the side of an input is chosen for providing a capture angle of a source radiation in the following limits:0.7/E1.5≦Ψ≦1.3/E1.5, (1)where ψ is a capture angle [rad];                E is a radiation energy of a used source [keV], thus a material of a reflecting surface of the channels for transmitting radiation includes the elements with an atomic number not more than 22, and a radiation energy of a used source is from 0.6 up to 6 keV.        
A relationship (1) is empirical; therefore to obtain a proper result the values appear in it should be expressed in the aforesaid terms.
It is preferable to use an X-ray tube with a rotating anode as a source of soft X-rays.